Traffic Controller

A Traffic Controller (TC) pool is a grouping of A or CNAME records that extends SiteBacker as a Global Server Load Balancing solution. Traffic Controller and SiteBacker pools are very similar in their makeup, therefore in this guide, certain tabs may be referred back to the SiteBacker section that has already explained their usage.

Creating an TC Pool

1. Select either an A record type, and then click the +Add Pool button.

2. Select Traffic Controller (TC) from the Select Pool Type drop-down menu.

3. Provide the Host and the Points To fields.

4. Click Save when finished.

Editing a TC Pool

Traffic Controller pools consists of various tabs of available functions and details that beyond just displaying associated records. So when editing a Traffic Controller pool, there are multiple sections that you can edit.

Pool Information

1. Once the pool is created, you will be taken to the Traffic Controller Pool display.

   1. You can also click the pencil icon next to the Traffic Controller pool from your records section to navigate to this section.

2. From the Pool Information tab, you will see the following details you can edit:

   1. Description– Defaults to the pool name.  The description can be a maximum of 255 characters.

   2. Pool Type– Displays if the pool is a Sitebacker pool, or a Traffic Controller pool. This field cannot be edited.

   3. Failover – Select Enabled if you want to enable a failover record, or Disabled if you wish to only serve the primary record.

   4. Probing– When probing is Enabled, a probe can be sent to verify that a URL can be reached, and that the record can be served.

      1. Note – Probing cannot be set to Disabled unless Failover is set to Disabled.

   5. Max Active to LB - Specifies the maximum number of active servers in the pool, and determines when Traffic Controller takes backup servers offline. For example, consider a pool with six servers. Setting Max Active to 4 means Traffic Controller takes two servers offline and sends the four active records in the answer.

   6. TTL - Specifies the Time to Live value for the pool.

   7. Configured - Displays the current number of records (including sub-pools) in the pool.

3. Click Save once you make any of your changes.

Records List

The Records List displays all of the currently associated records to the Traffic Controller pool. From this section, you can Add, Edit, or Delete records from the pool list as needed.

Add a Record

To add a new record to your pool:

1. Click the +Add Record button.

2. Provide the IP address or hostname for the record in the Points To field.

3. Select the Failover Delay value from the drop-down menu, which is measured in minutes.

4. Provide an even integer value for the Weight for the record.

   1. The Weight value determines the traffic load to send to each server in the pool.

5. Check the box to designate if this record will be a part of the All Fail record(s) or not.

6. Select the Probe Threshold value from the drop-down menu.

7. Select the Record State value from the drop-down menu.

8. Choose whether to Enable orDisable Probes for the record.

9. Provide an integer value for the Priority of the record.

10. Click Save when you are finished.

Records List

The Records list displays your current Traffic Controller pool records as follows:

• Points To - Displays the IPv4 address or hostname for the record.

• Record Type - The available record types can include A, SB (SiteBacker) / TC (Traffic Controller), or CNAME.

• Record State - Lists how the record should behave.

  • The default value, Normal, indicates that a pool record succeeds and fails with normal behavior (that is, SiteBacker serves records with the highest priority first).

  • Force Fail - Forces a record into a not-served state.

  • Force Active - Forces a record into a served state.

• Probing - Signifies if Probing is enabled for the record or not.

• Weight – The integer value that helps determine the traffic load that is sent to each server in the pool.

• Priority- Displays the priority value for the records, which is used to determine the order in which records are returned via the Response Method.

• Serving - Signifies if the record is Available to Serve or not (meaning if a probe was successful or not). A green check mark indicates that serving is available, while a red X indicates it is not.

Probe Definitions

For the Probe Definition details, please refer to the Sitebacker section Probe Types.

One key difference to note between the SiteBacker and Traffic Controller probes is that Traffic Controller provides Warning, Critical, and Fail specifications, whereas SiteBacker only provides Fail specifications.

Scheduled Events

For the Scheduled Events details, please refer to the Sitebacker section Scheduled Events.

Notifications

For the Notification details, please refer to the Sitebacker section Notifications.

Alerts

For the Alerts details, please refer to the Sitebacker section Alerts.

Data Flow

Each record in a Traffic Controller pool includes a weighted value that determines the traffic load to send to each server in the pool.

Traffic Controller sends e-mails to warn you when records have reached your configured threshold. If a record transitions to a critical state, Traffic Controller reduces the weighted value by 50%.

The following example shows a Traffic Controller pool with three records.

The 10.1.1.1 record is now in critical state. Traffic Controller continues to serve the record and reduces its weight by half (meaning Traffic Controller sends 50% less traffic to this server).

The 10.1.1.2 record has failed, so Traffic Controller brings up the 10.1.1.3 record. Because the record weights are equal, half the traffic goes to 10.1.1.1 and half to 10.1.1.3.

Traffic Controller Data Flow (critical states in dark brown

Sub-pools

You can add a pool as a record to another pool. The sub-pool (or chained pool) has its own records and probes and provides another backup and load balancing choice to SiteBacker/Traffic Controller.

A sub-pool is equivalent to a pool record from the perspective of the primary pool and it uses the same rules to determine whether to serve a record or another pool. If you query a primary SiteBacker pool’s name, you will receive all active records in the primary pool and—if the sub pool is active for the primary pool—all records in the sub-pool. However, if you query the sub-pool’s name, you receive only the sub-pool’s active records.

A sub-pool is equivalent to its set of pool records from the perspective of the DNS. For example, when a sub-pool is active in a primary pool, SiteBacker serves any active sub-pool records in addition to any other active records and sub-pools in the primary pool, but the sub-pool counts as one server, just like any pool record, when the primary pool calculates its maximum active servers.

Traffic Controller records have assigned weight values. If a Traffic Controller pool is an active sub-pool, the application evaluates the weight of each record and distributes the traffic accordingly.

UltraDNS supports an unlimited number of sub-pools up to five levels deep.

Sub-pool chains restricted to 5 levels